Coulomb parameters and photoemission for the molecular metal TTF-TCNQ

TL;DR

This study uses density-functional theory to determine Coulomb parameters for TTF-TCNQ, revealing significant long-range interactions that influence spectral properties and improve interpretation of photoemission data.

Contribution

It provides realistic extended Hubbard model parameters for TTF-TCNQ, including intra- and intermolecular screening effects, enhancing understanding of its electronic behavior.

Findings

Long-range Coulomb interactions are significant in TTF-TCNQ.

Inclusion of these interactions broadens spectral density.

Results improve interpretation of photoemission experiments.

Abstract

We employ density-functional theory to calculate realistic parameters for an extended Hubbard model of the molecular metal TTF-TCNQ. Considering both intra- and intermolecular screening in the crystal, we find significant longer-range Coulomb interactions along the molecular stacks, as well as inter-stack coupling. We show that the long-range Coulomb term of the extended Hubbard model leads to a broadening of the spectral density, likely resolving the problems with the interpretation of photoemission experiments using a simple Hubbard model only.